乙醇对南美白对虾N-乙酰-β-D-氨基葡萄糖苷酶活力与构象的影响  

Effect of Ethanol on Activity and Conformation of β-N-Acetyl-D-glucosaminidase from Prawn(Penaeus vannamei)

作　　者：王悦[1] 谢晓兰[1] 王勤[1] 陈清西[1] 

机构地区：[1]厦门大学生命科学学院细胞生物学和肿瘤细胞工程教育部重点实验室,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2004年第B08期28-31,共4页Journal of Xiamen University：Natural Science

基　　金：福建省青年科技人才创新项目(2004J054)资助

摘　　要：以南美白对虾为材料,分离提纯N 乙酰 β D 氨基葡萄糖苷酶,研究乙醇对该酶的活力与构象影响.结果表明,浓度低于22%(体积比)的乙醇对该酶活力有明显的激活效应;乙醇浓度为8%时,达到最大激活效应,酶活力为纯酶的180%.动力学研究表明,在30%浓度范围内,乙醇对酶活性的激活及抑制作用均是可逆的.乙醇低浓度下,Km值与Vmax值随乙醇浓度增大而增大;随着乙醇浓度的进一步升高,Km值保持不变,Vmax值则出现下降.紫外光谱与荧光光谱分析表明,低浓度乙醇对N 乙酰 β D 氨基葡萄糖苷酶的构象产生轻微的影响,而高浓度乙醇则使酶的整体构象趋于松散.由此可以推断,乙醇对该酶的活力影响是微扰酶活性中心产生激活效应与引发整体变构失活效应的共同作用结果.In this paper,the effects of ethanol on the activity and conformation of β-N-Acetyl-D-glucosaminidase(EC3.2.1.52)from prawn(Penaeus vannamei)were investigated.The results showed that the activatory and inhibitory effects of ethanol on the enzyme activity were reversible. In the range of 22%,the ethanol made enzyme activity increase.The enzyme activity increased to the maximum while the ethanol concentration was 8%.Further increasing the concentration of ethanol,the enzyme activity was inhibited and the IC_(50)(the inhibitor concentrations leading to 50% activity lost) was estimated to be 35%.Firstly,the values of K_m and V_(max) increased significantly along with the increasing of ethanol concentration,however,the higher ethanol concentrations made the value of K_m into constant and started to arouse a progressive decrease in V_(max).Ultraviolet and fluorescence measurements revealed that low concentration of ethanol produced slight changes in the conformation of the enzyme,but high concentration of ethanol resulted in loosing the tertiary structure of the enzyme.In conclusion,ethanol firstly changed the active center's microenvironment of NAGase which was probably responsible for the enzymatic activity,then changed the holistic conformation in the high concentration ethanol solvent,which led to the denaturation.

关 键 词：乙醇 南美白对虾 N-乙酰-Β-D-氨基葡萄糖苷酶 活力 构象 养殖 

分 类 号：S966.126[农业科学—水产养殖]